Process for the production of cyanamids



L. E. FRIDERICH.

PROCESS FOR THE PRODUCTION OF CYANAMIDS.

I 1 2 9 l 5 1 n a M d m n w a P a 0 wllw o D H N O .H A m H P A 2 SHEETS-SHEEN I.

L. E. FRIDERICH. PROCESS FOR THE PRODUCTION OF CYANAMIDS.

APPLICATION FILED OCT-1L I918.

Patented Mar. 15, 1921.

2 SHEETS-SHEE1 2 UNITED STATES LOUIS EUGENE FRIDERIGH, on Mars, FRANCE, ASSIGNOR T PATENT OFFICE.

LA socIE'rE FERDINAND GROS ET B OUGHARDY, OF PARIS, FRANCE.

PROCESS FOR THE PRODUCTION OF CY ANAMIDS.

Specification of Letters Patent.

Patented Mar. 15, 1921.

Application filed October 17, 1518. Serial No. 258,858.

(post-office address, 4 Rue Girardon,) have invented a new and useful Process for the Production of Cyanamids, which is fully set forth in the following specification.

This invention relates to the formation of cyanamid from calcium carbid and nitrogen; and its object, briefly stated, is the provision of an improved process which may be carried out more rapidly and with' larger resultant yields than is possible with the processes heretofore in use.

According to the invention, powdered carbid is deposited in boxes which are introduced successively into, and are, advanced automatically throu h, a suitable tunnel furnace, during whic time they are heated and subjected to the action of the nitrogen, the arran ement beingsuch that the reaction, whic is exothermic, is completed by the time the boxes reach the discharge end of the furnace. The boxes utilized are comparatively large and shallow, and the carbid is loosely deposited therein in thin layers, in order to expose to the heat as largeas possible a surface in proportion to the volume treated. The carbid is quickly'raised to the reaction temperature; but before such temperature is reached, the nitrogen, which is caused to flow through the furnace in a direction opposite to that traveled by the carbid boxes, has obtained free access to the carbid, the originally pulverulent mass sintering into a compact mass or body durin the reaction. The cyanamid is cooled as qulckly as possible after its formation; but this rapid cooling, however, is of less importance than the rapid heating, for the reason that,

decomposition takes place most rapidl when the material is in powdered form, w ich is the case during heating.

The accompanying drawings show one form of furnace in which the present process may be carried out, and in said drawm s:

igures 1, 1 and 1 constitute a longitudi nal vertical section of the furnace,

Figs. 2 and 3 are'transverse vertical sections on lines22 and 3-3, of Figs. 1 and 1*, respectively.

Referring more particularly to the drawings, the tunnel furnace thereinrepresented ing and movin carbid, and the removal 0 is constructed with a floor which comprises two fixed sections or parts 1, 1, spaced apart from each other to receive between them a central, longitudinal beam .2 covered with refractory material. This beam 2 is adapted to beraised and lowered by means of pairs of eccentrics 4 through the intermediary of transverse-beams 3, the eccentrics being operated by suitable shafting 17. The eccentries are provided with annular straps or collars 4 wherein they rotate, the straps of one pair of eccentrics being rigidly connected at their tops with the adjacent transverse beam 3, as indicated at 4 while the tops of the remaining pairs of straps are hinged as at 4 to the corresponding transverse beams. The eccentrics are represented in the drawings as at the top of their stroke, so that the cross-beams 3 and, hence, the central beam 2, occupy a. raised position, with the latter beam projecting above the surface of the floor; but in the normal position of parts, the eccentrics are lowered, and with them the beams 3 and 2, the upper surface of the beam 2 lyin below that of the floor, so that the carbi 'boxes 100 rest upon andare supported by the floor. At each revolution of the eccentrics, the aforementioned beams are lifted as above explained, with the result that the boxes are picked up by the central beam and raised above the floor; then, as the rotation of the eccentrics continues, the central beam, together with the boxes, will be moved in a forward direction through the furnace, it being understood that the boxes are loaded one after another upon the beam in some suitable manner; finally, the eccentrics start their downward movement, thereby lower- I back the central beam which, in turn, eposits the boxes upon the floor, the cycle of movements durin the working of the furnace.

Tig t joints between the furnace and the pit wherein the operating mechanism is arranged are effected by means of fixed iron sheeting 5 located beneath the cross-beams, and of leather bellows-like sheets 6 fixed t0 the upper surfaces of said beams and to the side walls of the furnace. To avoid the entry of air into the furnace during the charging of the boxes containinfg the powdered taming the 'cyanamid, two gas locks 7 and 8 are provided at the delivery and discharge continuing he boxes con-' lock chamber to expel the air.

'is then raised by means of a system of counter Weights 18, (which is also utilized to ends respectively of the furnace and constitute extensions of the furnace, these locks being isolated from the furnace by air-tight gates 10 and 9.

Considering now the actual process itself, the furnace is first heated to a high temperature by means ofsuitably-arranged carbon electrodesll, one of which is indicated, the

raise and lower the lock chamber cover, as will be understood from the dotted-line showing in Figs. 1 and 1 and, the box is finally forced into the furnace proper by the plunger mechanism 14. Thereupon the furnace gate 10 is closed again and a fresh box of carbid deposited in the lock chamber. The feeding mechanism comprising the eccentrics 4 and their operating shaftis then set in motion, and its speed regulated in any desired manner. Removal of the boxes c'ontaining the cyanamid takes place at the opposite end of the furnace, as will be understood,

the withdrawal of the boxes from the lock chamber 8 being effected by a second plunger mechanism 14' which is similar to the chargin mechanism 14, and the manipulation of t e cover 12' and gate 9' by a counterweight mechanism 13' similar to the mecha-'" nism 13 previously mentioned.

Safety valves 16 are preferably utilized to permit the escape of any explosive gases which may be formed as a result of faulty working, these valves being arranged in the roof of the furnace.

During the course of the operation, the nitrogen travels through the furnace in the opposite direction from the carbid boxes,

Once the reand a suitable exit is provided for the escape of any nitrogen which may be left after it has completed its traverse of the boxes; but in general the amount of nitrogen used is such as will be completely absorbed by the carbid; It will be seen that the electrodes 11 are located only, in the inlet portion or zone of the furnace, and are grouped comparatively close together adjacent the charging lock chamber, but are spaced farther and farther apart as they approach the central portion of the oven where the second zone commences. The action of the electrodes is, of course, to highly heat the walls of the furnace, )articularly the roof, the heating of the carbid being effected by radiation from said walls. In this way, the transformation of the carbid into cyanamid takes place rapidly, the crust of cyanamidinitially formed cracking and allowing access to the underlying carbid. Cooling takes place in the second half or zone of the furnace, and is rapidly effected, because of the fact that the progressive heating of the carbid is effected only at the rate at which it enters into reaction ;-that is to say, the reaction heat is transmitted layer by layer through the carbid, each successive layer cooling while the layers beneath it are reacting.

What I claim as new and desire to secure by Letters Patent of the United States is A process for the production of calcium cyanamid, consisting in inserting a charge of powdered calcium carbid into a furnace; heating solely the upper layer of the charge to reaction temperature and permitting such temperature to be transmitted exothermically from layer to layer down to the bottom layer and moving the charge progressively through the furnace against a current of nitrogen in such a manner that immediately the said upper layer has become converted into cyanamid the charge will have reached a cool zone of the furnace, so that such layer will be cooled while the successive layers below it are reacting layer by layer.

In testimony whereof I have signed this specification.

LOUIS EUGENE FRIDERICH.. 

